Isolation of macromolecules (e.g., nucleic acids, such as DNA or RNA, and proteins such as antibodies) is required before they can be used in many applications. For example, sequencing of nucleic acids and restriction digestion of nucleic acids requires or at least benefits from their purification. Nucleic acids can be purified via a variety of methods, including the traditional phenol-chloroform extraction. A relatively modern method of purifying nucleic acids makes use of magnetic beads. In this approach, magnetic beads are coated with a substance to which nucleic acids have affinity under certain conditions, and from which nucleic acids can be separated under different conditions. Employment of magnetic beads in this manner can eliminate a need for centrifugation steps or vacuum filtration steps, can speed up the process, can increase the yields of recovery, and can allow recovery of nucleic acids directly from an initial sample. Centrifugation and vacuum filtration have traditionally been difficult to automate. Magnetic beads can similarly be used for macromolecules other than nucleic acids; they can be used for proteins and complexes of two or more macromolecules.
Use of magnetic beads, for example while preparing samples for DNA sequencing, suffers from requiring collection of DNA from a relatively large volume, from the recovered DNA being diluted in the solution, and from the form of the recovery vessel being restricted based on the purification setup used. A need exists to improve time sensitive, high-throughput applications with the use of magnetic beads. Therefore, there is a need for improved apparatuses and methods that can enable purification of macromolecules in more concentrated solutions and within a wider variety of vessels.